In a semiconductor manufacturing process, cleaning of a wafer is a very important process to remove any impurity such as metal, organic matter, and fine particles that badly affect semiconductor characteristics. However, a wafer surface after cleaned and dried has many dangling bonds thereon which cause the surface to become very active. This produces a difficulty, for example, that the surface is again contaminated and a natural oxide film is nonuniformly formed thereon as the surface makes contact with air upon the wafer being carried. The present inventor has investigated a method of terminating dangling bonds on the wafer surface with hydrogen for stabilization of the wafer surface as a method of preventing the foregoing difficulty.
Such a hydrogen terminating method includes: 1) a method of subjecting a wafer to a dilute fluoric acid processing after a final cleaning process of the wafer for a ultra-pure water processing, 2) a method of processing a wafer with boiled ultra-pure water after final cleaning of the wafer, and 3) a method of processing a wafer in the atmosphere of hydrogen at a temperature of 600.degree. C. or more.
However, these methods are unlikely to completely terminate a wafer surface with hydrogen and are insufficient to prevent recontamination after cleaning.
Further, for drying a wafer, there are used a nitrogen blow and a rotary dryer or the like, however, they are unlikely to completely remove water molecules from the wafer surface and hence a nonuniform natural oxide film is produced.
In view of the drawbacks with the prior art, it is an object of the present invention to provide a wafer cleaning apparatus and a method thereof capable of preventing contamination of a wafer surface after cleaned and production of a natural oxide film on the wafer surface by completely terminating the wafer surface with hydrogen after cleaned.